If you selected "Start from another template", you'll then be prompted to select a template to clone. In this case, select your template and click "Continue".

If you selected "Clone an existing report", you'll then be prompted to select an existing report to clone. In this case, select from the list of reports and click "Continue".

With any of those three options, you'll then be presented with the main report template design editor, where you can add/customize sections and widgets just as you would when designing a standalone report.

Build the template to meet your business needs, then click "Save & Exit".